<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .box{
            height: 200px;
            background: red;
        }
        .v_m*{
            vertical-align: middle;
        }
        .v_m::after{
            content: '';
            display: inline-block;
            height: 100%;
            vertical-align: middle;
        }
    </style>
</head>
<body>
<div class="box v_m">
    <span>你好</span>
    <a href="">hello</a>
</div>

</body>
</html>